Wet Chemical Preparation Of 1-D β-FeOOH Nanorods And Nanorod Arrays As Well As Their Photocatalytic Property

With the growing public concern for environment, photocatalytic materials have been paid much attention in the field of environmental remediation. Although having been widely investigated, TiO2 can not operate in the visible light region as a result of wide band gap up to 3.1 eV. In comparasion,β-FeOOH has a narrower bandgap and could absorb the visible solar radiation. In addition, its features of large abundance in earth crust, low cost, and environmental benign make it be one of promising semiconductor photocatalytic materials. However, little scientific research work has been done onβ-FeOOH as a photocatalyst. This thesis focused on the the preparation and photocatalytic properties ofβ-FeOOH nanorods. Using methyl orange as a probe molecule, the photocatalytic performance dependence on pH of solutions, catalyst dosage and H2O2 additive was investigated. A two-step method was proposed to prepared one-dimensional nanorod arrays of iron oxyhydroxide. The main conclusions drawn in the thesis are as follows.1.1-Dβ-FeOOH nanorods with different morphologies have been prepared by using hydrothermal method, both of which demonstrated photocatalytic activity towards the degradation of methyl orange. The cross sections of the two samples are round and square, respectively. The influences of pH value, the dosage ofβ-FeOOH and H2O2 were studied by UV-vis spectrometry. The results show that:a) Lower pH value is in favor of the adsorption of dye molecules on the surface of catalysts, b) The surface area of photocatalyst is proportional to its dosage in the reaction system. Therefore, the photocatalytic degradation of MO molecules can benefit from the increasing the catalyst dosage, c) A proper amount of additive of H2O2 could improve the amount of·OH radicals in solution which are critical in photocatalytic reactions.2. Ordered arrays of one-dimensional nanorods ofβ-FeOOH have been prepared on glass substrate. A textured seed layer of iorn oxide was deposited on glass substrate to induce the anisotropic growth ofβ-FeOOH in solution. The seed layer could decrease interface tension caused by the crystal lattice mismatch between substrate and iron oxyhydroxide layer, and confines the growth space of the resultingβ-FeOOH nanorod arrays. The influences of pH value, substrate direction, reaction time on the final products were intensively studied and the reaction conditions were optimized to synthesize 1-D nanorod arrays. At the solution pH of 0.76, well orderedβ-FeOOH nanorods array films with the average diameter of 100nm and length of 800nm can be prepared at 95℃for 4h.